Hole cutter with chip egress aperture

ABSTRACT

A hole cutter has a substantially cylindrical blade body defining a blade body circumference, a cutting edge formed on one end of the blade body, and an axially-elongated slot formed through the substantially cylindrical blade body. The axially-elongated slot is configured to receive chips flowing from the cutting edge within the interior of the blade body and (i) into the slot, and/or (ii) through the slot, to prevent the collection of such chips within the interior of the blade body and/or at an interface between the blade body and work piece. The axially-elongated slot defines a first end adjacent to the cutting edge, a second end axially spaced further from the cutting edge, and a slot area. The hole cutter further defines a total slot area to blade body circumference ratio within the range of about 0.1 to about 0.3 depending on the size of the hole cutter.

FIELD OF THE INVENTION

The present invention relates to hole cutters, and more particularly, tohole cutters with apertures formed in the side walls thereof.

BACKGROUND INFORMATION

A typical prior art hole cutter includes a cylindrical blade bodydefining a plurality of saw teeth on the cutting edge of the blade body,and one or more apertures formed through an intermediate portion of theblade body. Typically, smaller diameter hole cutters have fewerapertures formed through the blade bodies, and larger diameter holecutters have more apertures formed through the blade bodies. Theapertures formed through prior art hole cutter blade bodies may define avariety of different configurations to facilitate inserting a tool intothe apertures, such as a screw driver, to remove circular work pieceslugs from the interiors of the blade bodies.

One of the drawbacks encountered with prior art hole cutters is thatchips or dust, particularly when cutting wood, collects within theinteriors of the hole cutters between the work piece slugs and the capson the non-working ends of the hole cutters. The apertures formed in theside walls of the blade bodies are designed to allow the insertion ofscrew drivers or like tools to remove work piece slugs, but are notconfigured to allow the chips or dust generated during cutting to flowthrough the apertures and away from the interiors of the blade bodies.The chips and dust that collect within the interiors of the blade bodiescan become compacted and rapidly fill the hole cutters. Chips and dustalso collect at the interfaces between the blade bodies and work pieces,such as between the external surfaces of the blade bodies and the workpieces. The chips and dust that collect at the interfaces of the bladesbodies and work pieces can become heated due to frictional forcescreated between the rotating blade bodies, collected chips and dust, andwork pieces. The thermal energy created by such frictional forces can besufficient to cause the paints or coatings on the external surfaces ofthe blade bodies to become soft or gooey. The collection of chips anddust within the interiors of the blade bodies and/or at the interfacesof the blade bodies and work pieces can significantly reduce the cuttingefficiency and overall cutting speed and/or blade life of such holecutters.

Although many prior art hole cutters include one or more aperturesformed through the side walls of the blade bodies, the apertures are notconfigured to facilitate the flow of chips from the interiors of theblade bodies into and/or through the apertures. In some such holecutters, the apertures are spaced too far from the cutting edge, suchthat the chips generated at the cutting edge become packed between theinterior of the blade body and the work piece slug prior to reaching theaperture(s). In other such hole cutters, the apertures are too small toallow any material volume of chips to flow into the apertures and/orthrough the apertures such that the apertures do not materially impactchip egress. In other such hole cutters, the apertures are notconfigured to cause the chips to flow into or through the apertures andaway from the cutting edge and interiors of the blade bodies.

Accordingly, it is an object of the present invention to overcome one ormore of the above-described drawbacks and/or disadvantages of the priorart.

SUMMARY OF THE INVENTION

In accordance with a first aspect, the present invention is directed toa hole cutter or hole saw for cutting a work piece. The hole cuttercomprises a substantially cylindrical blade body defining a blade bodycircumference, a cutting edge formed on one end of the blade body, andan axially-elongated aperture or slot formed through the substantiallycylindrical blade body. The axially-elongated slot is configured toreceive chips flowing from the cutting edge within the interior of theblade body and (i) into the slot, and/or (ii) through the slot, toprevent the collection of such chips within the interior of the bladebody and/or at an interface between the blade body and work piece. Theaxially-elongated slot defines a first end adjacent to the cutting edgeand axially spaced therefrom a first distance within the range of about15/100 inch to about ⅜ inch, a second end axially spaced from thecutting edge a second distance that is greater than the first distanceand is at least about one inch, and a slot area. The hole cutter furtherdefines one of the following: (i) the substantially cylindrical bladebody defines a diameter of about 13/16 inch or less, only one of theaxially-elongated slots is formed through the blade body, and the slotarea to blade body circumference ratio is at least about 0.15; (ii) thesubstantially cylindrical blade body defines a diameter within the rangeof about ⅞ inch to about 1 7/16 inches, only two of theaxially-elongated slots are formed through the blade body and areangularly spaced relative to each other, and the slot area to blade bodycircumference ratio is at least about 0.2; (iii) the substantiallycylindrical blade body defines a diameter within the range of about 1½inches to about 3⅜ inches, at least two of the axially-elongated slotsare formed through the blade body and are angularly spaced relative toeach other, and the slot area to blade body circumference ratio is atleast about 0.1; and (iv) the substantially cylindrical blade bodydefines a diameter of about 3½ inches or greater, more than two of theaxially-elongated slots are formed through the blade body and areangularly spaced relative to each other, and the slot area to blade bodycircumference ratio is at least about 0.1.

In the currently preferred embodiments of the present invention, thehole cutter defines one of the following: (i) the substantiallycylindrical blade body defines a diameter of about 13/16 inch or less,and the axially-elongated slot defines a slot area to blade bodycircumference ratio within the range of about 0.15 to about 0.25; (ii)the substantially cylindrical blade body defines a diameter within therange of about ⅞ inch to about 1 7/16 inches, and the twoaxially-elongated slots define a slot area to blade body circumferenceratio within the range of about 0.2 to about 0.33; (iii) thesubstantially cylindrical blade body defines a diameter within the rangeof about 1½ inches to about 3⅜ inches, and the two or moreaxially-elongated slots define a slot area to blade body circumferenceratio within the range of about 0.1 to about 0.33; and (iv) thesubstantially cylindrical blade body defines a diameter of about 3½inches or greater, and the two or more axially-elongated slots define aslot area to blade body circumference ratio within the range of about0.1 to about 0.25.

In some embodiments of the present invention, the hole cutter defines adirection of rotation that is the cutting direction of the cutting edge,and the first end of the axially-elongated slot defines an edge surfacethat slopes away from the cutting edge in a direction opposite thecutting direction. Preferably, the first end defines a maximum width ofat least about ⅖ inch, the sloped surface is at least about ⅖ inch long,and the sloped surface is at least one of curvilinear and rectilinear.In some such embodiments, the sloped surface is oriented at an acuteangle relative to an axis of the blade body within the range of about35° to about 60°.

In some embodiments of the present invention, the hole cutter defines adirection of rotation that is the cutting direction of the cutting edge,and the second end of the slot is angularly spaced relative to the firstend in a direction opposite the cutting direction. The axially-elongatedslot is oriented at an acute angle relative to an axis of the bladebody. The acute angle is preferably at least about 30°, and morepreferably is within the range of about 35° to about 60°.

In the currently preferred embodiments of the present invention, thehole cutter defines one of the following: (i) the diameter of thesubstantially cylindrical blade body is about 1 7/16 inches or less, andthe axially-elongated slot is oriented substantially parallel to an axisof the blade body, and (ii) the diameter of the substantiallycylindrical blade body is greater than about 1 7/16 inches, and eachaxially-elongated slot is oriented at an acute angle relative to an axisof the blade body and slopes away from the cutting edge in a directionopposite a cutting direction.

In accordance with another aspect, the present invention is directed toa hole cutter for cutting a work piece. The hole cutter comprises asubstantially cylindrical blade body defining a blade bodycircumference, a cutting edge formed on one end of the blade body, andmeans formed through the substantially cylindrical blade body forreceiving chips flowing from the cutting edge within the interior of theblade body and (i) into the means, and/or (ii) through the means, forpreventing the collection of such chips within the interior of the bladebody and/or at an interface between the blade body and work piece. Themeans defines a first end adjacent to the cutting edge and axiallyspaced therefrom a first distance within the range of about 15/100 inchto about ⅜ inch, a second end axially spaced from the cutting edge asecond distance that is greater than the first distance and is at leastabout one inch, and an area. The hole cutter defines one of thefollowing: (i) the substantially cylindrical blade body defines adiameter of about 13/16 inch or less, only one of said means is formedthrough the blade body, and the means area to blade body circumferenceratio is at least about 0.15; (ii) the substantially cylindrical bladebody defines a diameter within the range of about ⅞ inch to about 1 7/16inches, only two of said means are formed through the blade body and areangularly spaced relative to each other, and the means area to bladebody circumference ratio is at least about 0.2; (iii) the substantiallycylindrical blade body defines a diameter within the range of about 1½inches to about 3⅜ inches, at least two of said means are formed throughthe blade body and are angularly spaced relative to each other, and themeans area to blade body circumference ratio is at least about 0.1; and(iv) the substantially cylindrical blade body defines a diameter ofabout 3½ inches or greater, more than two of said means are formedthrough the blade body and are angularly spaced relative to each other,and the means area to blade body circumference ratio is at least about0.1.

In the currently preferred embodiments of the present invention, thehole cutter defines one of the following: (i) the substantiallycylindrical blade body defines a diameter of about 13/16 inch or less,and the means defines a means area to blade body circumference ratiowithin the range of about 0.15 to about 0.25; (ii) the substantiallycylindrical blade body defines a diameter within the range of about ⅞inch to about 1 7/16 inches, and the two means define a means area toblade body circumference ratio within the range of about 0.2 to about0.33; (iii) the substantially cylindrical blade body defines a diameterwithin the range of about 1½ inches to about 3⅜ inches, and the two ormore means define a means area to blade body circumference ratio withinthe range of about 0.1 to about 0.33; and (iv) the substantiallycylindrical blade body defines a diameter of at least about 3½ inches orgreater, and the three or more means define a means area to blade bodycircumference ratio within the range of about 0.1 to about 0.25. In thecurrently preferred embodiments, each means is an axially-elongatedaperture or slot.

One advantage of the hole cutters of the present invention is that thefirst ends of the axially-elongated slots or like means are axiallyspaced adjacent to the cutting edge a first distance within the range ofabout 15/100 inch to about ⅜ inch, and the second ends of the slots orlike means are axially spaced from the cutting edge a second distancethat is greater than the first distance. The second distance is at leastabout 1½ inches. As a result, the chips flowing from the cutting edgeswithin the interiors of the blade bodies are allowed to flow into theslots or like means and/or through the slots or like means to, in turn,prevent the collection of such chips within the interiors of the bladebodies and/or at an interface between the blade bodies and work pieces.The relatively close spacing of the first end of each slot or like meansto the cutting edge (about 15/100 inch to about ⅜ inch) facilitates theflow of chips into the slot or like means, and the depth of the slot orlike means from the cutting edge (at least about 1½ inches) facilitatesthe flow of chips into and/or through the slot or like means for a widevariety of work piece thicknesses. Yet another advantage of the holecutters of the present invention is that they define significant slotarea to cylindrical blade body circumference ratios of at least about0.1, and in many sizes of hole cutters, at least about 0.15 or 0.2,which in turn gives rise to substantial slot areas per given blade bodydiameters. As a result, the relatively large areas of the slots or likemeans, in combination with the close placement of the first or inletends of the slots or like means relative to the cutting edges of thehole cutters, facilitates the flow of chips into and/or through theslots, and in turn prevents the collection of such chips within theinteriors of the hole cutters. The relatively large slot areasfacilitate in preventing the slots from becoming clogged with chipsand/or allow the slots themselves to retain a significant volume ofchips, that otherwise would be trapped within the interiors of the bladebodies. Accordingly, the hole cutters of the present invention providesignificantly improved chip removal or egress from the interiors of theblade bodies in comparison to prior art hole cutters which, in turn, canlead to significantly improved cutting speeds and/or blade life. Anotheradvantage of some currently preferred embodiments of the presentinvention is that the slots or like means are oriented at acute anglesrelative to the axes of the hole cutters to facilitate the flow of chipsup and/or through the slots and thus away from the interiors of theblade bodies. Yet another advantage of some currently preferredembodiments of the present invention is that the first or inlet ends ofthe slots define edge surfaces that slope away from the cutting edge ina direction opposite the cutting direction of the hole cutters tofurther facilitate the flow of chips up and/or through the slots andthus away from the interiors of the blade bodies.

Other objects and advantages of the hole cutters of the presentinvention, and/or of the currently preferred embodiments thereof, willbecome more readily apparent in view of the following detaileddescription of the currently preferred embodiments and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a hole cutter embodying the presentinvention.

FIG. 2 is a side elevational view of the blade body of the hole cutterof FIG. 1 prior to being formed into a cylindrical shape.

FIG. 3 is a side elevational view of another embodiment of a blade bodyof the present invention prior to being formed into a cylindrical shape.

FIG. 4 is a table of parameters of exemplary hole cutters embodying thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In FIG. 1, a hole cutter embodying the present invention is indicatedgenerally by the reference numeral 10. The term “hole cutter” is usedherein to mean a tool that cuts holes in work pieces, such as wood ormetal work pieces, and includes without limitation hole saws. The holecutter 10 includes a blade body 12 defining a side wall 13. The bladebody 12 is shown in FIG. 2 in its flattened state; however, as shown inFIG. 1, the blade body 12 is rolled or otherwise formed into asubstantially cylindrical shape to form the hole cutter 10. As shown inFIG. 1, the side wall 13 extends around an axis of rotation “X” of thehole cutter 10 to define the substantially cylindrical blade body 12.One end of the blade body 12 is provided with a cutting edge 14 orientedsubstantially perpendicular to the axis of rotation X, and the opposingend of the blade body defines a rim 16. As shown in FIG. 1, a cap 17 isfixedly secured, such as by welding, to the rim 16 to enclose therespective end of the hole cutter 10, which is referred to herein as the“non-working” end of the hole cutter. The cap 17 includes a central hub28 defining a threaded aperture for threadedly engaging an arbor, aplurality of drive pin apertures 30 substantially equally spacedrelative to each other about the central hub 28 for engaging the drivepins of the arbor, and a pair of angularly-extending apertures 32 spacedabout 180° apart on opposite sides of the hub 28 relative to each other.The angularly-extending apertures 32 are dimensioned and positioned toallow insertion therein of a tool, such as a screw driver, to facilitatework piece slug removal.

As shown in FIGS. 1 and 2, the cutting edge 14 is defined by a pluralityof cutting teeth with gullets extending between the teeth. The cuttingteeth are configured to cut into a work piece when the cutter 10 isapplied to a work piece and rotated about the axis of rotation X in acutting direction. In the currently preferred embodiments, the cuttingedge 14 is a bi-metal cutting edge that includes a cutting edge whereinthe tips of the teeth are formed by a relatively hard metal, such astool steel, and the other portions of the teeth and blade body are madeof relatively softer steel, such as carbon steel. However, as may berecognized by those of ordinary skill in the pertinent art based on theteachings herein, the cutting edge 14 may be defined by any of numerousdifferent tooth forms or other cutting edge forms that are currentlyknown or that later become known. Similarly, although the blade body 12is shown as being formed from sheet metal that is rolled or otherwiseformed into the cylindrical blade body 12 and is, in turn, welded orotherwise attached to the cap 17, the hole cutter 10 may be formed inany of numerous other ways that are currently known, or that laterbecome known. For example, the end cap 17 and side wall 13 may be spun,drawn, molded or otherwise formed in one integral part.

As shown in FIGS. 1 and 2, the blade body 12 defines twoaxially-elongated apertures or slots 18 formed through the side wall 13thereof. As can be seen, the two slots 18 are angularly spaced relativeto each other on the cylindrical blade body 12. In the illustratedembodiment, the two slots 18 are approximately equally spaced relativeto each other, i.e., the two slots are spaced about 180° relative toeach other. Each axially-elongated aperture or slot 18 is configured toreceive therethrough a lever, such as a screw driver, for removal of awork piece slug located within the interior of the blade body 12. Invarious embodiments of the invention, each slot 18 has an axial depth D3(D2-D1) ranging from about 1⅛ inches to about 1⅘ inches. In theillustrated embodiment, each slot 18 has an axial depth D3 of about 1⅓inches. In certain embodiments, each slot 18 has a circumferentiallength L ranging from about ⅖ inch to about 1⅘ inches.

As shown in FIGS. 1 and 2, each slot 18 includes three fulcrums 20A, 20Band 20C axially and angularly spaced relative to each other. Thefulcrums 20A, 20B and 20C are defined by recessed radiused edge surfacesof the side wall 13 that are formed on the edge of the respective slot18 that is adjacent to, or on the side of, the non-working end of thehole cutter 10. The first fulcrum 20A is located adjacent to the cuttingedge 14, the second fulcrum 20C is spaced furthest from the cutting edge14 and located adjacent to the non-working end of the hole cutter and isangularly spaced from the first fulcrum 20A in a direction opposite tothe cutting direction, and the third fulcrum 20C is located axially andangularly between the first and second fulcrums 20A and 20C,respectively.

The number of slots 18 formed through the side wall 13 of the holecutter 10 depends on the size of the hole cutter. As a general rule, thelarger the diameter of the hole cutter, the greater is the number ofaxially-elongated apertures or slots 18 that can be formed through thecylindrical blade body 12. In the currently preferred embodiments of thepresent invention, relatively small diameter hole cutters (e.g., about9/16 inch in diameter to about 13/16 inch in diameter) have one slot 18oriented substantially parallel to the axis X of the hole cutter, largerdiameter hole cutters have two slots 18 (e.g., about ⅞ inch in diameterto about 1 7/16 inches in diameter) oriented substantially parallel tothe axis X of the hole cutter, still larger diameter hole cutters (e.g.,about 1½ inches in diameter to about 3⅜ inches in diameter) have twolarger area slots 18 that are oriented at acute angles relative to theaxis X of the hole cutter, and still larger diameter hole cutters (e.g.,about 3½ inches in diameter to about 6 inches in diameter) have fourlarger area slots 18 oriented at acute angles relative to the axis X ofthe hole cutter. In the embodiment of FIGS. 1 and 2, the diameter of thehole cutter 10 is sufficient to include two axially-extending slots 18oriented at acute angles relative to the axis X of the hole cutter.Accordingly, each axially-extending slot 18 shown in FIGS. 1 and 2 isoriented at an acute angle “A” with respect to the axis X of the holecutter. In the currently preferred embodiments, the angle A is at leastabout 30°, and is preferably within the range of about 35° to about 60°.In the illustrated embodiment, the acute angle A is about 47°. As may berecognized by those of ordinary skill in the pertinent art based on theteachings herein, these angles are only exemplary, and any of numerousother angles equally may be employed.

In the currently preferred embodiments of hole cutters having multipleslots 18, the slots 18 are approximately equally spaced relative to eachother about the axis X of the hole cutter, i.e., if there are two slots18 they are angularly spaced about 180° relative to each other, if thereare three slots 18 they are angularly spaced about 120° relative to eachother, if there are four slots 18 they are angularly spaced about 90°relative to each other, etc. However, as may be recognized by those ofordinary skill in the pertinent art based on the teachings herein, theslots 18 need not be equally spaced relative to each other, nor do allapertures or slots 18 on the same hole cutter need to define the sameaperture or slot configuration or size.

As shown in FIGS. 1 and 2, each slot 18 defines a first or inlet end 22that is adjacent to the cutting edge 14, and a second or outlet end 24that is axially spaced further away from the cutting edge 14 than thefirst end 22 and is angularly spaced relative to the first end 22 in adirection opposite to the cutting direction. The first end 22 is axiallyspaced from a plane defined by the cutting edge 14 a first distance D1within the range of about 15/100 inch to about ⅜ inch. One advantage ofthis configuration is that the inlet end 22 of each axially-extendingslot 18 is spaced closely adjacent to the cutting edge 14 to receivechips flowing from the cutting edge 14 within the interior of the bladebody 12 and into the slot 18 and/or through the slot 18, to, in turn,prevent the collection of such chips within the interior of the bladebody 12 and/or at an interface between the blade body 12 and work piece.Yet another advantage of this configuration is that the angularorientation of the axially-extending slots 18 facilitates in allowingthe chips to flow up through the slots 18 and away from the cutting edge14 and interior of the blade body 12 as the hole cutter 10 is rotatedduring a cutting operation. A further advantage of the illustrated bladebody 12 is that the inlet end 22 of each slot 18 is axially spacedadjacent to the cutting edge 14 such that a solid or substantially solidannular portion 26 of the blade body 12 extends annularly about theblade body and axially between the cutting edge 14 and the first end 22of each slot 18. This annular portion 26 of the blade body 12advantageously provides the blade body 12 with sufficient strength towithstand the heat applied to the blade body 12 during the manufacturingof the hole cutter without distorting the blade body, and providessufficient strength to the hole cutter 12 to withstand the forcesencountered during cutting operations. However, the annular portion 26of the blade body 12 is sufficiently thin (as indicated above, D1 iswithin the range of about 15/100 inch to about ⅜ inch) to allow thechips and dust generated at the cutting edge 14 to flow into the slots18 and away from the interior of the blade body 12. In the currentlypreferred embodiments, the outlet or second end 24 of each slot 18 isaxially spaced from the cutting edge a second distance D2 of at leastabout 1 inch, and preferably at least about 1½ inches. In theillustrated embodiment, the distance D2 is about 1¾ inches.

The term “chip” is used herein to mean small particles of a work pieceformed upon cutting the work piece with the hole cutter, and includingwithout limitation, saw dust, wood dust, wood chips, metal dust, metalchips, dust and/or chips created upon cutting work pieces formed ofmaterials other than wood or metal, and/or including materials orcomponents in addition to wood or metal.

In the illustrated embodiment, the distances D1 and D2 are measured froma plane extending between the tips of unset teeth. However, as may berecognized by those of ordinary skill in the pertinent art based on theteachings herein, these distances, or the distances between otherfeatures of the hole cutter 10 and the cutting edge 14, may be measuredwith respect to any of numerous other reference lines or features thatare currently known or used, or that later become known or used, such asfrom the base of the deepest gullets of the cutting teeth.

As shown in FIG. 2, each axially-extending aperture or slot 18 includesa sloped side edge surface 28 that is angled away from the cutting edge14 in a direction opposite the cutting direction and spaced opposite thefulcrums 20A, 20B and 20C. In the illustrated embodiment, the slopedside edge 28 of each slot 18 is substantially smooth and rectilinear tofacilitate sliding movement of a tool into and through the slot 18(e.g., from one fulcrum 20A, 20B or 20C to another to progressivelyremove a slug) and to facilitate chip and/or dust egress through theslot 18. The sloped side edge 28 is spaced from the fulcrums 20A, 20Band 20C such that each slot 18 defines a minimum width W1 of about 0.27inch to allow insertion and translation of a number 2 screwdrivertherethrough.

As described above and shown in FIGS. 1 and 2, the angled or sloped edgesurface 28 is angled with respect to the axis X of the hole cutter fromthe first or inlet end 22 to the second or outlet end 24 in a directionopposite the cutting direction. Therefore, in such an arrangement asshown in FIGS. 1 and 2, the diameter of the substantially cylindricalblade body 12 is at least about 1½ inches, the second or outlet end 24of the slot 18 is angularly spaced relative to the first or inlet end 22such that the slot 18 slopes away from the cutting edge 14 in adirection opposite to the cutting direction, and the slot 18 is orientedat an acute angle relative to the axis of rotation X of at least about30°.

In FIG. 3, another embodiment of a blade body of the present inventionis indicated generally by the reference numeral 112. The blade body 112is shown in its flattened state; however, as shown in FIG. 1 withrespect to the blade body 12 of FIG. 1, and as will be recognized bythose of ordinary skill in the pertinent art based on the teachingsherein, the blade body 112 is rolled or otherwise formed into asubstantially cylindrical shape to form a hole cutter. The blade body112 is substantially the same as the blade body 12 described above inconnection with FIGS. 1 and 2, and therefore like reference numeralspreceded by the numeral “1” are used to indicate like elements. Theprimary difference of the blade body 112 in comparison to the blade body12 described above is that the two axially-extending apertures or slots118 formed in the blade body 112 are oriented substantially parallel tothe axis of rotation X of the hole cutter. In the illustratedembodiment, the blade body 112 is used to form “small diameter” holecutters defining blade body diameters within the range of about ⅞ inchto about 1 7/16 inches. As the blade body 112 forms a relatively smalldiameter hole cutter, the slots 118 cannot define as large a slot areaas the larger diameter hole cutters described above, and/or cannot beoriented at acute angles relative to the axis of rotation X of the holecutter. The currently preferred embodiments of smaller diameter holecutters (e.g., about 13/16 inch in diameter or less) define the sameslot configuration as illustrated in FIG. 3, but include only one suchslot 118. Thus, the blade body 12 of FIGS. 1 and 2 forms a “largediameter” hole cutter (a hole cutter defining a diameter of at leastabout 1½ inches), while the blade body 112 of FIG. 3 forms a “smalldiameter” hole cutter (a hole cutter defining a diameter less than 1½inches).

Another difference of the blade body 12 in comparison to the blade body112 described above is in the configuration of the sloped edge surface128 of the first or inlet end 122 of each slot 118. As can be seen, thefirst or inlet end 122 of each slot 118 is defined by two curvilinearregions. A first curvilinear region is contiguous to a side edge of thefirst fulcrum 220A and is defined by one or more relatively small radiiR1. A second curvilinear region is contiguous to the first curvilinearregion and is defined by one or more larger radii R2. As can be seen,the larger radius R2 imparts a shape to the respective edge of the slot118 that slopes away from the cutting edge 114 in a direction oppositethe cutting direction of the blade 112. In addition, the location andorientation of the first fulcrum 120A, the respective side and thesloped edge surface imparts a relatively wide inlet 122 to the slot 118to facilitate the flow of chips or dust from the cutting edge 114 intothe slot 118. In the illustrated embodiment, the width W2 at the inlet122 of the slot 118 is within the range of about ⅕ to about ⅗ inch, andin the illustrated embodiment is about ⅖ inch.

As shown in the table of FIG. 4, the hole cutters of the presentinvention define significant slot area to cylindrical blade bodycircumference ratios of at least about 0.1, and in many sizes of holecutters, at least about 0.15 or 0.2, which in turn gives rise tosubstantial slot areas per given blade body diameters. The relativelylarge areas of the slots 18, 118, in combination with the closeplacement of the first or inlet ends 22, 122 of the slots relative tothe cutting edges 14, 114 of the hole cutters, facilitates the flow ofchips into and/or through the slots, and in turn prevents the collectionof such chips within the interiors of the hole cutters. Accordingly, asshown in FIG. 4, in the illustrated embodiments, the number of slotsand/or the configurations of the slots vary depending upon the diametersof the hole cutters in order to maximize the slot area to cylindricalblade body circumference ratios of the hole cutters, and in turnfacilitate chip egress into and/or through the slots and thereby improvethe cutting efficiency and/or blade life of the hole cutters.

The terms “nominal shell area” and “nominal circumference” in FIG. 4relate to the “size” of the hole cutters. The “size” of a hole cutter isused herein to mean the diameter of the hole that the cutter will cutinto a work piece. Therefore, the nominal diameters and nominalcircumferences of the hole cutters shown in FIG. 4 are not the actual,measurable diameters and circumferences of the blade bodies, but ratherare the diameters and circumferences of the holes formed by the holecutters in work pieces. For example, the cutting teeth of a certain sizecutter may be angled or set radially outwardly relative to the side wallof the blade body, and therefore the cutter will create a hole in a workpiece that defines a diameter that is larger than the diameter of theblade body. Accordingly, the “size” of a particular hole cutter can varyfrom the diameter of the cylindrical blade body of the hole cutter.However, because the measurable dimensions of the blade body of mosthole cutters differ from the corresponding “sizes” of the hole cuttersby relatively small or insignificant amounts, the “nominal shell area”and the “nominal circumference” are useful metrics. In FIG. 4, thenominal circumference was calculated by multiplying each hole cutter'ssize (the diameter of a hole created by the hole cutter) by 2π.Similarly, the nominal shell area was calculated by multiplying thenominal circumference by the nominal height of the shell or blade body,which in the illustrated embodiments was about 1.866 inches.

As shown in FIG. 4, the ratio of the total slot area to the nominalcircumference of the hole cutters, calculated as described above, variesdepending on the size of the hole cutter, but is at least about 0.1inch. The slots 118 shown in FIG. 3 are referred to herein as “smallerconfiguration” slots, and the slots 18 of FIG. 2 are referred to hereinas “larger configuration” slots. In the currently preferred embodiments,all smaller configuration slots are the same size and shape regardlessof the diameters of the smaller hole cutters, and all largerconfiguration slots are the same size and shape regardless of thediameters of the larger hole cutters.

The currently preferred embodiments of “small” hole cutters definingdiameters of about 13/16 inch or less include only one smallconfiguration slot 118 formed through the blade body. These “small” holecutters define a slot area to blade body circumference ratio that is atleast about 0.15, and more preferably is within the range of about 0.15to about 0.25. The area of each small configuration slot is within therange of about 3/10 inch to about ½ inch, and in the illustratedembodiments, the area of each smaller configuration slot 118 is about ⅖inch. As described above, the smaller configuration slots 118 areoriented substantially parallel to the axis X of the hole cutter.

As also shown in FIG. 4, the currently preferred embodiments of the“small” hole cutters defining diameters within the range of about ⅞ inchto about 1 7/16 inches include two smaller configuration slots 118formed through the blade body and angularly spaced relative to eachother. These “small” hole cutters define a slot area to blade bodycircumference ratio that is at least about 0.2, and more preferably iswithin the range of about 0.2 to about 0.33. Each small configurationslot 118 of these “small” hole cutters is the same size andconfiguration as the slots 118 of the smaller diameter hole cutters(i.e., having diameters of about 13/16 inch or less); however, becausethese hole cutters are larger they include two such smallerconfiguration slots. The total area of the smaller configuration slots118 of these “small” hole cutters is within the range of about ⅗ toabout 1 inch, and in the illustrated embodiments, the total area of theslots is about ⅘ inch. As shown in FIG. 3, the smaller configurationslots 118 of these “small” hole cutters are oriented substantiallyparallel to the axis of rotation X of the hole cutters.

As further shown in FIG. 4, the currently preferred embodiments of“larger” hole cutters defining diameters within the range of about 1½inches to about 3⅜ inches include two larger configuration slots 18formed through the blade body and angularly spaced relative to eachother. The slot area to blade body circumference ratio of these largerdiameter hole cutters is at least about 0.1, and more preferably iswithin the range of about 0.1 to about 0.33. The currently preferredembodiments of these larger diameter hole cutters include two largerconfiguration slots 18 angularly spaced about 180° relative to eachother. The area of each larger configuration slot 118 is within therange of about ½ inch to about 0.625 inch, and in the illustratedembodiments is about 0.564 inch. Accordingly, the area of the two largerconfiguration slots 18 is within the range of about 1 inch to about 1¼inches, and in the illustrated embodiments, is about 1⅛ inches. Asdescribed above, each larger configuration slot 18 is oriented at anacute angle relative to the axis of rotation X of the respective holecutter.

As also shown in FIG. 4, the currently preferred embodiments of “large”hole cutters defining diameters of about 3½ inches or greater includefour larger configuration slots 18 formed through the blade body andangularly spaced about 90° relative to each other. Each of these“larger” hole cutters defines a slot area to blade body circumferenceratio that is at least about 0.1, and more preferably is within therange of about 0.1 to about 0.25. The currently preferred embodiments ofthese larger diameter hole cutters include two larger configurationslots 18 angularly spaced about 180° relative to each other. The area ofthe four larger configuration slots 18 is within the range of about 2inches to about 2½ inches, and in the illustrated embodiments, is about2¼ inches. As described above, each larger configuration slot 18 isoriented at an acute angle relative to the axis of rotation X of therespective hole cutter.

One advantage of the combination of the location of the inlet or firstends of the slots in relation to the cutting edge (such as the distancebetween a plane defined by the tips of unset cutting teeth and the inletedge), the orientation of the slots (such as being angled with respectto a plane defined by the axis of the cutter at an acute angle of atleast about 30° and/or including a sloped surface angled away from thecutting direction), and the relatively large slot area to circumferenceratios, is that the slots provide for more efficient and effective chipejection, and therefore, increased cutting efficiency. Another advantageof the hole cutters of the present invention is that the slots can beconfigured to allow the chips generated during cutting to flow throughthe slots and away from the interiors of the blade bodies. Yet anotheradvantage of the hole cutters of the present invention is that the slotscan prevent the hole cutters from being overcome by the rate at whichthe chips are generated during cutting and can allow for the properegress of chips away from the interiors of the hole cutters and/or theinterfaces between the blade bodies and work pieces.

The hole cutters of the present invention may include one or morefeatures of the hole cutters disclosed and/or claimed in any of thefollowing co-pending patent applications that are assigned to theassignee of the present invention and are hereby expressly incorporatedby reference in their entireties as part of the present disclosure: U.S.patent application Ser. No. 12/687,065, filed on even date herewith andentitled “Hole Cutter with Axially-Elongated Aperture Defining MultipleFulcrums”; U.S. patent application Ser. No. 12/687,073, filed on evendate herewith and entitled “Hole Cutter With Minimum Tooth Pitch toBlade Body Thickness Ratio”; U.S. patent application Ser. No.12/687,102, filed on even date herewith and entitled “Hole Cutter WithExtruded Cap”; U.S. patent application Ser. No. 12/687,052, filed oneven date herewith and entitled “Coated Hole Cutter”; U.S. Design patentapplication Ser. No. 29/353,762, filed on even date herewith andentitled “Hole Saw”; and U.S. Design patent application Ser. No.29/353,759, filed on even date herewith and entitled “Hole Saw”.

It may be readily understood by those having skill in the pertinent artfrom the present disclosure that any of numerous changes andmodifications may be made to the above-described and other embodimentsof the present invention without departing from the scope of theinvention as defined in the appended claims. For example, the holecutters may be made from any of numerous different materials, in any ofnumerous shapes, taking any of numerous different dimensions. Forexample the cutting edge may be made from any of numerous differentmaterials or combinations of materials that are currently known or thatlater become known. As an example, the cutting edge may be a bi-metalcutting edge, such as bi-metal cutting teeth. As another example, thecutting edge may take any form, pattern, arrangement or configurationthat is currently known or that later becomes known, including withoutlimitation tooth patterns that tend to function well in specificapplications, hybrid applications or general applications. For example,the cutting teeth may define any of numerous different tooth forms,pitch patterns and/or set patterns. As another example, a singleaperture may be provided in the body of the cutter, two or moreapertures may be angularly and/or axially aligned with one another, ortwo or more apertures may be variably spaced angularly and/or axiallyrelative to one another. In addition, the hole cutters may definedifferent numbers of axially-elongated apertures, different apertureconfiguration, shapes and/or sizes than those disclosed herein. Also,the hole cutters may be used in any of numerous different cuttingapplications, on any of numerous different work piece materials, such aswoods, metals, plastics, composites, resins, stones, fabrics, foams,etc. Further, the blade body may not define any elongated apertures orslots, or the apertures or slots may not be contained within the sidewalls of the cutters. For example, the apertures may extend to thecutting edge, the top rim of the side wall or cap, or may extend to boththe cutting edge and top rim of the side wall or cap to define a channelthat extends the entire or substantially entire axial extent of theblade body. For another example, the apertures may include fewer thanthree fulcrums, or more than three fulcrums. As another example, thesloped surface of the inlet portion of the apertures may be curvilinear,rectilinear and/or a combination of curvilinear and rectilinear edgesurface regions. Alternatively, the first or inlet end of the slot neednot be sloped. Accordingly, this detailed description of the currentlypreferred embodiments of the present invention is to be taken in anillustrative, as opposed to a limiting sense.

What is claimed is:
 1. A hole cutter for cutting a work piece,comprising a substantially cylindrical blade body defining a blade bodycircumference, a cutting edge formed on one end of the blade body, andan axially-elongated slot formed through the substantially cylindricalblade body and configured to receive chips flowing from the cutting edgewithin an interior of the blade body and at least one of (i) into theslot, and (ii) through the slot, to prevent the collection of such chipswithin at least one of the interior of the blade body and an interfacebetween the blade body and the work piece, wherein the substantiallycylindrical blade body includes at least one protrusion formed along aside edge of the axially-elongated slot such that the axially-elongatedslot includes at least one fulcrum extending therein, wherein theaxially-longated slot defines a first end adjacent to the cutting edgeand axially spaced therefrom a first distance selected to be within therange of about 15/100 inch to about ⅜ inch, a second end axially spacedfrom the cutting edge a second distance that is greater than the firstdistance and selected to be at least about one inch, and a slot area,wherein one of (i) the substantially cylindrical blade body defines adiameter of about 13/16 inch or less, only one of the axially-elongatedslots is formed through the blade body, and a slot area to blade bodycircumference ratio is selected to be at least about 0.15; (ii) thesubstantially cylindrical blade body defines a diameter within the rangeof about ⅞ inch to about 1- 7/16 inches, only two of theaxially-elongated slots are formed through the blade body and angularlyspaced relative to each other, and a slot area to blade bodycircumference ratio is selected to be at least about 0.18; (iii) thesubstantially cylindrical blade body defines a diameter within the rangeof about 1-½ inches to about 3-⅜ inches, at least two of theaxially-elongated slots are formed through the blade body and angularlyspaced relative to each other, and a slot area to blade bodycircumference ratio is selected to be at least about 0.1; and (iv) thesubstantially cylindrical blade body defines a diameter of about 3- 1/2inches or greater, more than two of the axially-elongated slots areformed through the blade body and angularly spaced relative to eachother, and a slot area to blade body circumference ratio is selected tobe at least about 0.1.
 2. A hole cutter as defined in claim 1, whereinone of (i) the substantially cylindrical blade body defines a diameterof about 13/16 inch or less, and the axially-elongated slot defines aslot area to blade body circumference ratio within the range of about0.15 to about 0.25; (ii) the substantially cylindrical blade bodydefines a diameter within the range of about ⅞ inch to about 1- 7/16inches, and the two axially-elongated slots define a slot area to bladebody circumference ratio within the range of about 0.18 to about 0.33;(iii) the substantially cylindrical blade body defines a diameter withinthe range of about 1-½ inches to about 3-⅜ inches, and the at least twoaxially-elongated slots define a slot area to blade body circumferenceratio within the range of about 0.1 to about 0.33; and (iv) thesubstantially cylindrical blade body defines a diameter of about 3-½inches or greater, and the more than two axially-elongated slots definea slot area to blade body circumference ratio within the range of about0.1 to about 0.25.
 3. A hole cutter as defined in claim 2, wherein thehole cutter defines a direction of rotation that is a cutting directionof the cutting edge, and wherein the first end of the axially-elongatedslot defines a sloped edge surface that slopes away from the cuttingedge in a direction opposite the cutting direction.
 4. A hole cutter asdefined in claim 3, wherein the first end of the axially-elongated slotdefines a maximum width of at least about ⅖ inch, wherein the slopededge surface is at least about ⅖ inch long, and wherein the sloped edgesurface is at least one of curvilinear and rectilinear.
 5. A hole cutteras defined in claim 4, wherein the sloped edge surface is oriented at anacute angle relative to an axis of the blade body within the range ofabout 35° to about 60°.
 6. A hole cutter as defined in claim 2, whereinthe hole cutter defines a direction of rotation that is a cuttingdirection of the cutting edge, and wherein the second end of theaxially-elongated slot is angularly spaced relative to the first end ofthe axially-elongated slot in a direction opposite the cuttingdirection.
 7. A hole cutter as defined in claim 6, wherein theaxially-elongated slot is oriented at an acute angle relative to an axisof the blade body.
 8. A hole cutter as defined in claim 7, wherein theacute angle is at least about 30°.
 9. A hole cutter as defined in claim8, wherein the acute angle is within the range of about 35° to about60°.
 10. A hole cutter as defined in claim 1, wherein the cutting edgeis defined by a plurality of saw teeth including tips and gulletsbetween the tips, and wherein the first distance is measured from either(i) a deepest gullet of the cutting edge, or (ii) a plane extendingbetween tips of unset teeth of the cutting edge.
 11. A hole cutter asdefined in claim 10, wherein the second distance is at least about 1-½inches.
 12. A hole cutter as defined in claim 1, wherein theaxially-elongated slot defines a minimum width of about 0.27 inch toallow insertion of a number 2 screwdriver therethrough.
 13. A holecutter as defined in claim 1, wherein the cutting edge is bi-metal. 14.A hole cutter as defined in claim 1, wherein one of (i) the diameter ofthe substantially cylindrical blade body is about 1- 7/16 inches orless, and the axially-elongated slot is oriented substantially parallelto an axis of the blade body, and (ii) the diameter of the substantiallycylindrical blade body is greater than about 1- 7/16 inches, and eachaxially-elongated slot is oriented at an acute angle relative to an axisof the blade body and slopes away from the cutting edge in a directionopposite a cutting direction of the cutting edge.
 15. A hole cutter asdefined in claim 1, wherein the blade body defines a wall regionextending annularly about the blade body and extending axially betweenthe cutting edge and the first end of the slot a distance within therange of about 15/100 inch to about ⅜ inch.
 16. A hole cutter forcutting a work piece, comprising a substantially cylindrical blade bodydefining a blade body circumference, a cutting edge formed on one end ofthe blade body, and means formed through the substantially cylindricalblade body for receiving chips flowing from the cutting edge within aninterior of the blade body and at least one of (i) into the means, and(ii) through the means, for preventing the collection of such chipswithin at least one of the interior of the blade body and an interfacebetween the blade body and the work piece, wherein the substantiallycylindrical blade body includes at least one protrusion formed along aside edge of the means such that the means includes at least one fulcrumextending therein, wherein the means defines a first end adjacent to thecutting edge and axially spaced therefrom a first distance selected tobe within the range of about 15/100 inch to about ⅜ inch, a second endaxially spaced from the cutting edge a second distance that is greaterthan the first distance and selected to be at least about one inch, anda means area, wherein one of (i) the substantially cylindrical bladebody defines a diameter of about 13/16 inch or less, only one of themeans is formed through the blade body, and a means area to blade bodycircumference ratio is selected to be at least about 0.15; (ii) thesubstantially cylindrical blade body defines a diameter within the rangeof about ⅞ inch to about 1- 7/16 inches, only two of the means areformed through the blade body and are angularly spaced relative to eachother, and a means area to blade body circumference ratio is selected tobe at least about 0.18; (iii) the substantially cylindrical blade bodydefines a diameter within the range of about 1-1/2 inches to about 3-⅜inches, at least two of the means are formed through the blade body andare angularly spaced relative to each other, and a means area to bladebody circumference ratio is selected to be at least about 0.1; and (iv)the substantially cylindrical blade body defines a diameter of about 3-½inches or greater, more than two of the means are formed through theblade body and are angularly spaced relative to each other, and a meansarea to blade body circumference ratio is selected to be at least about0.1.
 17. A hole cutter as defined in claim 16, wherein one of (i) thesubstantially cylindrical blade body defines a diameter of about 13/16inch or less, and the means defines a means area to blade bodycircumference ratio within the range of about 0.15 to about 0.25; (ii)the substantially cylindrical blade body defines a diameter within therange of about ⅞ inch to about 1- 7/16 inches, and the two means definea means area to blade body circumference ratio within the range of about0.18 to about 0.33; (iii) the substantially cylindrical blade bodydefines a diameter within the range of about 1-½ inches to about 3-⅜inches, and the at least two means define a means area to blade bodycircumference ratio within the range of about 0.1to about 0.33; and (iv)the substantially cylindrical blade body defines a diameter of about 3-½inches or greater, and the more than two means define a means area toblade body circumference ratio within the range of about 0.1 to about0.25.
 18. A hole cutter as defined in claim 16, wherein the means is anaxially-elongated slot.
 19. A hole cutter as defined in claim 16,wherein the means includes a plurality of fulcrums extending therein.20. A hole cutter as defined in claim 1, wherein the axially-elongatedslot includes a plurality of fulcrums extending therein.